Researcher David Redish at the University of Minnesota in Minneapolis set up a “restaurant row” for his lab rats. The “restaurants” consisted of four stops where the rat could receive one option of his favorite flavor foods — banana, cherry, chocolate and a fourth unflavored food. The rat stops at the entrance and presses a button, which made a sound. The pitch indicated how long the rat needed to wait for food, anywhere from one to 45 seconds. If the rat was impatient, it could walk to the next stop and try again. However, each rat had an hour to get through the course, so it needed to be efficient.

To watch how these decisions manifested in the brain, Redish and his colleagues wired electrodes into the rats’ brains, so they could monitor the neural activity in the orbitofrontal cortex. Specific neural patterns indicated which foods the rats were thinking about at the time.

The experiment replicates a common human dilemma, Redish said. You go to a restaurant, discover it has a long wait and decide to go somewhere else, only to find your second choice restaurant has an even longer wait.

To the researcher’s surprise, when the rat got a “bad deal” it immediately turned around and looked back at its first choice. It’s neural pattern changed, and it thought of the first-choice food.

But regret is not just wishfully thinking about the past. Redish found that the regretful rats were more likely to wait longer for a “bad deal” than they would normally. They also ate their less-desirable treat more quickly. A few of the rats learned from their mistake and their neural activity showed them planning their next food stop.

Which leads Redish to wonder: “Humans avoid regret. Do rats?”

Left:
"Forty-five minute wait? Rats! I should have made reservations." Photo by Flickr user Rebecca Lai